RE: DRSSTC design procedure - draft

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Steve Conner" <steve.conner-at-optosci-dot-com> 

 >I will use a large toroid, with, say, 50 pF of capacitance. I will
 >assume that the energy in the self-capacitance of the secondary coil is
 >included in this too, and that it also contributes for the bang energy,
 >what is probably not true.

I believe that the energy in the secondary self-capacitance _does_
contribute, and what's more, any energy in the primary tank at the time of
breakout contributes too. I actually think this is the secret of the
DRSSTC's efficiency. In Steve Ward's successful self-resonant designs, the
primary tank is full of energy at breakout. Jimmy H. originally tuned his in
a similar way to what you suggest, to get energy "transfer" in the classical
sense, but he found the spark output improved a lot when he retuned it to
drive at one of the resonances.


 >Mode 31:33:35 results in k=0.12 and energy transfer in 8.25 cycles.
 >(The formula for k is a bit complicated to list here, but is
 >implemented in my sstcd program.)

This is very interesting. The system I've been playing with had k=0.11, but
C1=12.5nF and L1=42uH. I tried exciting it at various frequencies but the
lower resonance seemed to give the best results. When tuned in this way it
took about 30 cycles to produce a decent spark. The peak primary current was
about 400A, the bang energy something like 5-6 joules and the spark output
was 36".

It hit 36" regularly and would have probably gone even further, if it hadn't
exploded on the first run.


 >there is always a design as the one above that
 >requires less input current to transfer the same energy in the same
 >number of cycles (or I think so...).

According to your method then, I should be able to get the same spark output
with 200A peak current in 8.25 cycles? I need to check this out. My coiling
stuff is all dismantled at the moment, but I can run a PSpice simulaion of
the two coils side by side.

If the improvement that this design method gives is as drastic as you
suggest, then we could find a way of living with the hard switching that is
an inevitable consequence if you don't drive the system at one of the
resonances.

Steve C.